1. Field of the Invention
Embodiments relate to an epoxy curable composition for producing an anisotropic conductive film (hereinafter, also referred to as an ‘anisotropic conductive film composition’ or simply as an ‘ACF composition’), an anisotropic conductive film including the same, and associated methods.
2. Description of the Related Art
An anisotropic conductive film (ACF) generally refers to a film-like adhesive in which conductive particles are dispersed in an electrically insulating adhesive resin. Generally, the anisotropic conductive film may be positioned between circuits, followed by heating/pressing under specific conditions to electrically connect circuit terminals of the circuits. The electrically insulating adhesive resin fills a space between the adjacent circuit terminals and electrically isolates the conductive particles from one another. Generally, anisotropic conductive films are widely used to electrically connect LCD panels or printed circuit boards (PCBs) to tape carrier packages (TCPs).
With recent trends towards large-area and thin displays, spaces between electrodes and circuits are becoming gradually narrower. Anisotropic conductive films play a very important role in interconnecting microcircuit terminals. Under these circumstances, anisotropic conductive films have received a great deal of attention as connection materials for chip-on-glass (COG) mounting, chip-on-film (COF) mounting, etc.
Conventional anisotropic conductive films include two types, i.e. epoxy and acrylic. A typical epoxy anisotropic conductive film is produced by mixing a binder resin system acting as a matrix for film formation with a cure system composed of an epoxy or phenolic resin and a curing agent, and a typical acrylic anisotropic conductive film is produced by mixing a binder resin system with a cure system composed of (meth)acrylic oligomer or monomer and a radical initiator.
The epoxy anisotropic conductive film has excellent initial physical properties due to the inherent characteristics of the epoxy resin, and exhibits good reliability due to the presence of a number of aromatic benzene rings within a network structure after curing. However, since the production of the epoxy anisotropic conductive film requires a very high reaction temperature and a long reaction time, there are difficulties in controlling processing factors and in the maintenance and repair of a connection system. To solve such processing-related problems, encapsulated latent curing agents and cationic curing agents that can lower the reaction temperature and shorten the reaction time of epoxy resins have been developed in recent years. However, when defects are found in a device incorporating the anisotropic conductive film, good adhesiveness inherent to the epoxy resin and a number of aromatic benzene rings present within the network structure make it very difficult to remove the anisotropic conductive film, making re-work difficult.